Circuit breaker



March 24, 1931- M. J. GRAHAM ET AL CIRCUIT BREAKER Filed Fb. 18. 1929Patented Mar. 24, 1931 UNITED STATES PATENT OFFICE MICHAEL J. GRAHAM ANDARTHUR HOLSEY, OF CHICAGO, ILLINOIS, ASSIGNORS TO INTERNATIONALHARVESTER- COMPANY, A CORPORATION OF NEW JERSEY CIRCUIT BREAKERApplication filed February 18, 1929. Serial No. 340,717.

This invention relates to circuit breakers. Ignition systems derivingenergy from magneto generators or the like usually employ a circuitbreaker structure to induce a hot spark for ignition purposes inengines, for example. These circuit breakers are quite conventional andembody a cam ring, manually adjustable within a sleeve, and frictionallyheld in contact therewith, to regulate the time of sparking by advancingor retarding the cam ring relative to the breaker.

Eventually, it has been found, the repeat ed turning of the cam ringcauses wear so that it no longer frictionally engages in the sleeve tomaintain the desired advanced or retarded position.

Accordingly, it is the primary object of this invention to improve thestructure and operation of circuit breakers of the kind used inconnection with magneto or other current generators.

Another object is to provide structure for the adjustable cam ring thatwill automatically compensate for any wear thereon, or on the sleevewhich carries the ring, so that the ring and sleeve will at all times bein proper frictional engagement.

Other objects will be apparent as the disclosure continues. Thesedesirable objects in the illustrative embodiment of the invention to bedisclosed are accomplished in the provision of an elongated depressionin the outer surface of the cam ring, said depression receiving,loosely, a stiff flat spring element, arcuated to a more pronouncedcurvature than the curve of the cam ring. Thus, with the spring in thedepression, the cam ring will have to be forced into the bearing sleeve,the pressure causing the spring element initially to flatten slightly sothat it is caused to assume a curve substantially coincident with theouter curved surface of the ring. The ring is now in operative positionand capable of turning movement in the bearing sleeve. As wear takesplace between the ring and bearing sleeve surfaces, the spring elementautomatically corn-- pensates for such wear because it moves outradially from its depression to engage yieldingly against the sleeve.This action maintains the two cooperative parts in frictional engagementat all times, as can now be readily understood.

In the accompanying sheet of drawings showing an illustrative embodimentof the invention,

Figure 1 is a face view of a part of the circuit breaker assembly asapplied to a magneto generator, the view being along the section line1-1 seen in Figure 2, when looking in the direction of the arrows;

Figure 2 is a vertical cross sectional View of the same structure asviewed along the line 2 2 of Figure 1, looking in the direction of thearrows;

Figure 3 is a detached, inner face view of the cap and adjusting armpart Figure 4 is a perspective view of the cam ring per se; and,

Figure 5 is a detailed, cross sectional view, on an enlarged scale. toillustrate the compensating spring in place in the cam ring de pression.

In these drawings a magneto generator has been generally illustrated at10. A mounting plate 11 including a carrier sleeve 12 is secured bybolts 13 to the magneto. The carrier sleeve 12 has arranged therein theusual bearing sleeve 14 which includes a flange 15 carrying a stop setscrew 16 for a purpose later to appear.

Arranged in the bearing sleeve 14 for frictional turning movementtherein is the usual cam ring 17 having the usual inner, diametricallyopposed cam surfaces 18. An adjuster cap 19 having an operating controlarm 20 formed therewith is turnably mounted by means of the flange 21 onthe carrier sleeve 12.

The cap also includes an inner flange 22 having tongues 23 forengagement in complementary cut outs 24 so that when the cap, by meansof the arm 20, is advanced or retarded, the same turning movement willbe communicated to the cam ring which regulates the circuit breaker. Thecircuit breaker has not been illustrated, as this is well known in theart. A cut out 25 in the cam ring cooperates with the set screw 16 tolimit the angular distance through which the cam ring may be adjusted.

After a time, the repeated adjustment of the cam ring in the bearingsleeve causes the touching surfaces to wear, which destroys thefrictional contact, making a loose cam ring fit and preventing the camring from being effectively maintained in any desired adjusted position.In the past, this wear necessitated replacement of the cam ring.

The present invention provides an automatically acting wear compensatorstructure which materially prolongs the life of the cam ring andovercomes the difficulties heretofore encountered due to suchobjectionable Wear.

Accordingly, in the illustrative form of the invention a depression orgroove 26 is formed preferably on the outer wear surface of the camring, the depression having end walls 27'. Arranged in this depressionis a flat, stiff spring element 28 performed to a curvature somewhatmore pronounced than the curvature of the outer surface of the cam ring.The spring element is of a length to cause its ends normally to stopshort of the end Walls of the depression. See Figure 5.

It can now be seen that, when the cam ring is frictionally fitted intothe bearing sleeve, the spring element 28 will be flattened or distortedfrom its performed shape. The ends of the spring element 28 are thuscaused to abut the end walls 27 of the depression 26.

The parts are thus assembled for use. lVhen the cap member 19 is turned,the cam ring is also turned to vary the time of operat-ion of thecircuit breaker to advance or retard the sparking action in the wellknown I manner. These repeated adjustments of the cam rmg cause wear ofthe outer surface of the ring and also of the adjoining bearing sleevesurface. Such wear obviously destroys the frictional contact betweenthese parts and is highly ob ectionable because v friction alone isrelied upon to hold the cam ring in adusted position. With the provisionof the spring of this invention any such wear will be automaticallytaken up, or compensated for, because the spring element 28, when weartakes place, presses radially out because of its inherent tendency torestore itself to the initial preformed shape. The incident springpressure, therefore, causes the parts described to be retained infrictional contact, which is so desirable and necessary. In practice thecam ring is made of steel, and the bearing sleeve of brass and aluminum.Heat and cold effect expansion and contrac tion of these partsdifferently. Thus, the structure of this invention willalso compensateautomatically for these changes and cause the cam ring properly to fitin the bearing sleeve.

It must now be appreciated that this invention accomplishes all of thedesirable objects heretofore recited.

Obvious changes may be'r'esorted to by sure and tending to resume itsinitial preformed shape as wear takes place between the sleeve and ringto compensate for such wear and retain said parts infrictionalengagement.

2. In a circuit breaker, an annular hearing sleeve, an annular cam ringfrictionally retained therein and adapted for angular adjustmentrelative thereto, a relatively short groove provided in the outersurface of the ring, said groove having end walls, a short flat springarranged loosely in the groove and preformed to the curve of an are lessthan the curvature of the ring, said spring adapted to be distorted, bypressure to conform to the curve of the ring with its ends abutting theend walls of the groove, whereby the ring with the spring may befrictionally fitted into the sleeve, said spring gradually resuming itsinitial preformed curvature as wear takes place between the sleeve andrin In testimony whereof we a-fliX our signa tures.

' ARTHUR HOLSEY.

MICHAEL J. GRAHAM.

